In this report, we inform in detail on fabrication of a special (3 rings of air-holes) index-giuding air-silica microstructured optical fiber (IG MOF) with different air-hole diameters in the cladding (irregular cladding) and its application for a broadband supercontinuum (SC) generation by femtosecond laser pulses. For comparison, supercontinuum generation in a special nonlinear air-silica IG MOF with regular cladding is also investigated. Dispersion properties of the investigated fibers were numerically predicted and experimentally verified. Broadband SC generation from visual wavelengths up to 1600 nm in such fibers, both with the length of 1 m, was observed.

In this work, we show a design of a laboratory exercise in which a digital camera has been coupled to a Michelson interferometer based on free-propagation arms. By using the camera, our students measure the evolution of the interference patterns as a function of the difference between the optical paths of the arms. In this way, they obtain the corresponding reduction of the contrast of the fringes. The analysis of the results allows one to calculate the coherence length, and also to relate the temporal coherence of the employed laser with its spectral line profile. The exercise has been carried out with two lasers, which present different coherence lengths.

Fabry-Perot (F-P) interferometers are commonly studied in undergraduate textbooks. Their spectral transmittance profiles are usually analyzed assuming that a plane wave is incident on the interferometer. This wave undergoes multiple reflections on the interferometer surfaces, and the interference of all these waves leads to the typical resonance structure of the spectral transmittance profile described by the Airy formula. However Fabry-Perot interferometers are commonly used in conjunction with laser beams, for example when they are used as intracavity-wavelength and longitudinal mode-selecting etalons. Although it is evident that the finite size of the beam will produce a deterioration of the filtering characteristics of the F-P interferometer, this effect is not usually analyzed in undergraduate textbooks. The aim of this work is to show students how the finite size of the incident beam influences the spatial and spectral response of the F-P interferometer. In particular it will be shown that the spectral response of the F-P interferometer can significantly differ from that predicted by the Airy formula. The theoretical approach is based on a plane-wave angular spectrum representation of the incident, transmitted, and reflected beams. The incident beam is assumed to be gaussian and the cases of normal and oblique incidence are discussed.

In this manuscript we show the design of a simple experiment that reproduces the operation of the Michelson stellar interferometer by using step-index polymer optical fibers. The emission of stellar sources, single or binary stars, has been simulated by the laser light emerging from the output surface of the 2 meter-long polymer optical fiber. This light has an emission pattern that is similar to the emission pattern of stellar sources - circular, uniform, spatially incoherent, and quasi-monochromatic. Light coming from the fiber end faces passes through two identical pinholes located on a lid covering the objective of a small telescope, thus producing interference. Interference fringes have been acquired using a camera that is coupled to a telescope. The experiments have been carried out both outdoors in the daytime and indoors. By measuring the fringe visibilities, we have determined the size of our artificial stellar sources and the distance between them, when placing them at distances of 54 m from the telescope in the indoor measurements and of 75 m in the outdoor ones.

This paper provides an analysis of the emission properties of different polymer optical fibers doped with organic materials with the aim of investigate their performance as luminescent solar concentrators. We present a study of the light propagation along the fibers, together with the experimental measurements of two different efficiencies: side illumination coupling efficiency and fluorescent fiber solar concentrator efficiency. The results obtained for all the fibers are compared and discussed.

The emission properties of rhodamine-6G doped step-index cladded and uncladded thermoset fibres have been studied for a transversal excitation configuration. Measurements include a deep analysis of the amplified spontaneous emission and a detailed study of the optical gains of the fibres by using the Variable-Stripe Length method. The evolution of the emission spectra as a function of the propagation distance has also been reported for both one-photon emission and twophoton emission. Comparisons of the results of the cladded fibres with those of the uncladded ones are presented and discussed.

One of the issues that affects the performance of plastic optical fibers (POFs) is the light scattering caused by the presence of inhomogeneities in the polymer, which is responsible for the optical energy loss and for the mode coupling in POFs. The aim of this work is to compare two different methods for measuring light scattered in step index polymer optical fibers (SI-POF) by using the side-illumination technique. On the one hand, scattered intensity and far-field patterns at single wavelength have been measured by varying the launching conditions: position of the excitation spot in the fiber and incidence angle. On the other hand, we have measured the spectral distribution of the scattered light in SIPOFs by exciting the fiber with a supercontinuum source. A theoretical model based on Mie theory has been used to analyze the obtained experimental results. From this analysis, the size and position of the most influential scattering centers in step-index POFs can be estimated. The results obtained employing both methods have been compared, resuming the advantages and drawbacks of each one for characterizing the optical quality on SI-POFs.

The polarisation state of light may be exploited in single-mode polymer mPOFs for sensing purposes.
The bend-induced birefringence varies linearly with the inverse square of the bend radius, whereas the
twist-induced polarisation rotation varies linearly with the bre twist angle. Both e ects are highly reproducible and show higher sensitivity than their glass counterparts.

In this work we perform a detailed experimental and theoretical analysis of the properties of amplified spontaneous
emission (ASE) in a rhodamine-6G-doped graded-index polymer optical fiber when the fiber is pumped either
longitudinally or transversally with respect to the fiber axis. The dependence of the ASE threshold and efficiency on
fiber length has been compared for both schemes of excitation. A theoretical model for longitudinal excitation has been
carried out by means of the laser rate equations as functions of time, distance traveled by light and wavelength. The
analysis takes into account that the fiber is a typical graded-index POF in which the radial distributions of light power
density and dye concentration are not uniform. The theoretical calculations agree satisfactorily with the experimental
results. The photodegradation of the ASE intensity has also been measured for both pumping schemes.

The aim of this work is to analyze the propagation of the emitted light in fluorescent POFs by using the side-illumination
technique. In particular, we have studied the angular distribution of the emitted light as a function of the launching angle
and of the height of the incident beam. A theoretical model has been developed in order to explain the experimental
measurements. A good agreement between the theoretical and the experimental results has been obtained both
qualitatively and quantitatively. It is shown that both the theoretical and the experimental critical angles are appreciably
higher than the meridional one corresponding to the maximum acceptance angle for a single source placed at the fiber
axis. This increase changes the value of several important parameters in the performance of active fibers. The analysis
has been performed in polymer optical fibers doped with a conjugated polymer.

The relations between radiometric magnitudes and quantities associated to optical properties of materials (processes of reflection, transmission and emission of radiant flux by or through material media) have been analyzed. By studying some particular examples, we illustrate the dependence of optical properties of materials on the radiometric magnitude chosen and it is shown that quantities obtained from a radiometric point of view differ mathematically and physically from the corresponding Optics expressions.

We present in this paper the detailed design, development, and implementation of two optical measurement systems that serve as teaching devices for undergraduate students. The building of both prototypes has been carried out by several students for their undergraduate thesis project. Both systems are highly modular and each of their functional blocks are clearly separated and labeled so that students can immediately identify their constituent parts. In both cases, the hardware consists of optoelectronic devices and mechanical parts that are fully automated and controlled by the corresponding Windows application developed ad hoc. Our Optical Spectrum Analyzer is, as far as we know, the first system designed for highly multimode polymer optical fibers operating in the visible region. As for the Optical Time Domain Reflectometer, it is not only suitable for educational experimental measurements, but it can also be compared with commercial systems, since it works in the second transmission window.

In this work we report an experimental demonstration of broadband wavelength self-tuning in Rb5Nd(MoO4)4 laser crystal (RNM) together with a theoretical treatment of the system based on its birefringence properties. The experimental self-frequency tuning of the laser emission along the free spectral range of the RNM crystal (1060-1070 nm) was obtained by rotating the birefringent gain plate in its own plane. To investigate the tuning characteristics of the spectral filter, we have used the Jones-vector formalism. The calculated wavelength-selective tuning matches very precisely the experimental observations.

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Journal of Applied Remote SensingJournal of Astronomical Telescopes Instruments and SystemsJournal of Biomedical OpticsJournal of Electronic ImagingJournal of Medical ImagingJournal of Micro/Nanolithography, MEMS, and MOEMSJournal of NanophotonicsJournal of Photonics for EnergyNeurophotonicsOptical EngineeringSPIE Reviews